A secondary battery has been popularly used as a power source for electronic equipment such as a mobile phone or IT equipment in addition to an application where a primary battery is replaced with a secondary battery. Particularly, a nonaqueous electrolyte secondary battery represented by a lithium ion secondary battery possesses high energy density and hence, the application of the nonaqueous electrolyte secondary battery to electrical equipment such as an electric vehicle has been in progress. In this case, aiming at the outputting of high energy and the acquisition of large capacity, the secondary batteries have been used in the form of a power source module in general.
The power source module is formed of a cell stack in which a plurality of secondary batteries are arranged as battery cells, and electrode terminals of the respective batteries are connected in the cell stack. Due to such a configuration, the power source module functions as one power source of high voltage and large capacity (see JP-A-2009-048965 including FIG. 1, for example).